Abstract

Earlier papers in this series have discussed the interaction between two coplanar dislocationtype cracks and between coplanar cracks that form an infinite periodic sequence, the stability criteria being determined. This paper examines the stability of an infinite periodic sequence of noncoplanar dislocation-type cracks, particular consideration being given to the determination of the complete fracture criterion. Unlike the situation that exists for coplanar dislocation-type cracks, some aspects of the results are radically different depending on whether the mode of deformation is anti-plane strain, plane strain shear, or plane strain tension, and the different characteristics of the three models are emphasized. With the antiplane strain model exact solutions can be obtained, but with both plane strain shear and plane strain tension models, the governing singular integral equations can only be solved when the cracks are widely spaced.